The present invention relates to a carbon dioxide gas (CO2) incubator or a multigas incubator as an incubator for incubating cultures (samples) such as cells, microbes and the like.
The incubator maintains a temperature and a CO2 concentration constant therein (in incubation room) and keeps its inside in a sterile condition to incubate cultures (samples) such as cells or microbes as incubation targets. Therefore, the inside of the incubator must be periodically processed by sterilization treatment. There has been a multigas incubator provided with a heater and its controller for adjusting the temperature in the incubation room (storing room), gas supply means for supplying and controlling supply gases such as CO2, O2 and the like for controlling concentrations of gases, and a humidifying tray for adjusting the humidity, respectively for the purpose of incubating samples in the incubation room.
On the other hand, as disclosed in Japanese Patent Application Laid Open Nos. 31,462/1995 and 166,536/2000, there have been incubating devices each comprise an outer box provided on its inner side with a heat insulating material for uniformly and effectively heating the inside of an inner box to improve its temperature-returning characteristics, the inner box arranged inside the outer box with a space more inside than the heat insulating material, and a heating device secured in the space in contact with the inner box for heating the inside thereof. The space described above serves to form an air layer (air jacket) provided for the thermal insulation between the incubation room of the incubator and its outside and promotion of heat transfer by natural convection. As shown in the latter patent literature, particularly, a humidifying tray is arranged at the bottom of the incubation room for storing humidification water for controlling the humidity in the incubation room.
On the other hand, a multigas incubator accommodates therein important and valuable cells, microbes or the like to be incubated so that variations in humidity in the incubation room cannot be avoided by the ambient air entering the incubator when an inner door is opened. Taking account of the fact that variations in humidity adversely affect samples such as cells and the like to be incubated, it is needed to shorten the time as much as possible, which is required to return a desired humidity after the inner door is once opened and then closed (that is, humidity-returning time). In the case incubating human cells for ectosomatic fertilization or animal fertile eggs as samples, particularly, these samples are likely to be remarkably affected by humidity so that extra precautions are required. In the incubators for treating such samples, the concentration of O2 is frequently set and kept at approximately 5%, and dried N2 gas is supplied into an incubation room after closing the door in order to control the concentration of O2. Consequently, the humidity-returning time would be adversely prolonged by such a supply of the dried gas.